Smoking experts say wearing the patch for 10 weeks is insufficient for most smokers

(Health.com) -- If you're trying to quit smoking, wearing a nicotine patch for up to six months -- far longer than is generally recommended -- may increase your chances of staying smoke-free, a new study has found.

Even with the longer treatment, however, your chances of successfully quitting are only about one in seven, according to the study, which was funded by the National Cancer Institute and the National Institute on Drug Abuse.

"There's an assumption that nicotine dependence is an acute disease that can be treated with short-term therapy," says Caryn Lerman, one of the study's authors and the director of the Tobacco Use Research Center at the University of Pennsylvania. "Smokers should talk to their health-care provider about whether it makes sense for them to continue on the nicotine patch for an extended period of time as an alternative to returning to smoking."

The patch reduces cravings and withdrawal symptoms by releasing a slow and steady dose of nicotine through the skin. The latest guidelines from the U.S. Public Health Service recommend that smokers who are trying to quit use the patch for eight weeks or less, although some brands of patches are designed to be used for up to 10 weeks.

In the new study, published this week in the Annals of Internal Medicine, 568 adult smokers who were otherwise healthy wore a 21-milligram nicotine patch (Nicoderm CQ brand) for eight weeks. At that point, half of the smokers continued to wear the nicotine patch for an additional 16 weeks, while the others wore an identical placebo patch for the same amount of time.

After 24 weeks, 32 percent of the participants who received the nicotine patch for the duration hadn't smoked in the previous week, compared to just 20 percent of those who received the placebo patch. (Whether the participants had smoked that week was verified by checking a breath sample for carbon monoxide.)

The longer nicotine treatment also proved more effective when a stricter measure of quitting was used. At the 24-week mark, 19 percent of the people who wore the patch throughout hadn't smoked even one cigarette since quitting, compared with 13 percent in the placebo group.

People who wore the patch for a full 24 weeks were also more inclined to try to quit again if they temporarily fell off the wagon, the researchers found. "If somebody has a slip and smokes a few puffs or even has a whole cigarette, they'll be more likely to return to abstinence if they're on the nicotine patch," Lerman says.

After one year, however, there was no significant difference between the two groups in the percentage of study participants who remained smoke free. Just 14 percent of the people in either group hadn't smoked a cigarette in the previous week -- underscoring just how hard it is to kick the nicotine habit.

Many smoking-cessation experts have come to believe that wearing the patch for eight to 10 weeks is insufficient for most smokers. In its 2008 guidelines, the U.S. Public Health Service called for more research into the effectiveness of longer-term nicotine replacement therapy. Lerman and her colleagues are now conducting another study in which quitting smokers will wear the patch for an entire year.

There's no evidence that wearing the patch for an extended period is unsafe, says Robert A. Schnoll, the lead author of the current study. The two groups of participants in the study showed no significant differences in side effects, he points out. And, Schnoll says, "Everyone would agree that it's safer than smoking."

Nicotine patches deliver a relatively pure dose of the drug, while cigarettes contain chemical additives that have been shown to cause cancer.

Jonathan Foulds, the director of the Tobacco Dependence Program at the University of Medicine and Dentistry of New Jersey, in New Brunswick, says the study's findings should prompt experts to reconsider how they help people quit smoking.

"We should tailor the duration of pharmaceutical treatment for smoking cessation to the client's needs, rather than what the box says," says Foulds, who wasn't involved in the study. "It's clear that what the box says may not be long enough for some patients."

Foulds has his patients stay on the patch until they go a full two weeks without any cigarette cravings or withdrawal symptoms. At that point, he weans them off the patch by using progressively smaller sizes.

"There's nothing magical about 24 weeks," he says. "The point is that staying on [nicotine replacement therapy] helps you stay off cigarettes -- and, it seems, the longer the better."

Every smoker is different, according to Lerman. Some can quit with brief treatment, she says, but others will need to stick with nicotine replacement therapy for a longer time. People who experience very severe withdrawal symptoms, for example, are likely to be better off with longer-term use, she says.